Fungicidal compositions containing N-Acetonylbenzamides

ABSTRACT

The present invention relates to fungicidal compositions and their use as a method for controlling phytopathogenic fungi comprising the application of a selected fungicidally active N-acetonylbenzamide compound and a second fungicidally active compound selected from the group consisting of an inhibitor of respiration at cytochrome complex III, ziram, fluazinam, zarilamide, chlorothalonil, propamocarb, folpet, fosetyl-aluminum or a fungitoxic metabolite thereof, a triphenyltin type fungicide and a copper containing fungicide to plant seed, to plant foliage or to a plant growth medium. The compositions and method of use provide higher fungicidal activity than separate use of the same compounds.

This is a divisional application of Ser. no. 09/148,604, filed Sep. 4, 1988, now U.S. Pat. No. 6,004,947, which claim for domestic priority 60/072725 filed Jan. 27, 1998.

The present invention relates to new fungicidal compositions and their use as a method for controlling phytopathogenic fungi on plants.

It is always desirable to improve products which can be used by growers in order to combat fungal diseases of crops, and in particular diseases caused by fungi in the class Oomycetes.

It is also always desirable to reduce the doses of chemical products spread into the environment to combat fungal attacks on crops, in particular by reducing the application doses of the products.

It is also always desirable to increase the number of antifungal products available to growers in order that they will find, among these products, the one which is best suited to the grower's specific use.

One objective of the invention is thus to provide novel fungicidal compositions which are useful against the problems outlined above.

Another objective of the invention is to propose novel fungicidal compositions which are useful in the preventive and curative treatment of diseases caused by fungi of the class Oomycetes.

Still another objective of the invention is to propose novel fungicidal compositions which are of improved efficacy against mildew and/or late blight caused by Oomycetes.

Yet another objective of the invention is to propose novel fungicidal compositions which are of improved efficacy against downy mildew in grapes and other crops and/or late blight in tomatoes and potatoes.

It has now been found that these objectives may be achieved, partly or totally, by means of the fungicidal compositions according to the present invention.

U.S. Pat. Nos. 5,304,572 and 5,677,333 disclose applying mixtures of the N-acetonylbenzamides disclosed therein with other fungicidal compounds. It has now been discovered that application of the N-acetonylbenzamides disclosed in these patents in combination with selected other fungicidal compounds provides unexpectedly high fungicidal activity and is effective in controlling phytopathogenic fungi at lower N-acetonylbenzamide dosage rates than those disclosed in the U.S. Pat. No. 5,304,572 patent. Although U.S. Pat. No. 5,677,333 discloses the use of N-acetonylbenzamides in combination with ethylene bisdithiocarbamates, cymoxanil and dimethomorph to provide unexpectedly high fungicidal activity, the synergistic combinations of this invention are not disclosed or suggested in that patent.

In a first embodiment of this invention, there is provided a composition comprising

(a) a fungicidally effective amount of a first fungicidally active compound having the formula (I) ##STR1## or an agronomically acceptable salt thereof wherein

R¹ and R³ are each independently halo or (C₁ -C₄)alkyl,

R² is (C₁ -C₄)alkyl, (C₂ -C₄)alkenyl, (C₂ -C₆)alkynyl, (C₁ -C₄)alkoxy or cyano,

R⁴ and R⁵ are each independently a hydrogen atom or (C₁ -C₄)alkyl, provided that at least one of R⁴ and R⁵ is (C₂ -C₄)alkyl and

X is halo, thiocyano or isothiocyano;

(b) a fungicidally effective amount of a second fungicidally active compound selected from the group consisting of

(i) an inhibitor of respiration at cytochrome complex III, such as a methoxyacrylate type fungicide, for example, azoxystrobin and kresoxim-methyl,

(ii) ziram

(iii) fluazinam

(iv) zarilamide

(v) chlorothalonil

(vi) propamocarb

(vii) folpet

(viii) fosetyl-aluminum or a fungitoxic metabolite thereof such as phosphorus acid,

(ix) a triphenyltin type fungicide such as fentin hydroxide and fentin acetate and

(x) a copper containing fungicide such as copper(I) sulfate, copper(II) sulfate, copper(II) sulfate pentahydrate, copper(I) oxide and Bordeaux mixture; and

(c) an agronomically acceptable carrier.

In a second embodiment of this invention, there is provided a method for controlling phytopathogenic fungi on a plant comprising the application of

(a) a fungicidally effective amount of a first fungicidally active compound having the formula (I) ##STR2## or an agronomically acceptable salt thereof wherein

R¹ and R³ are each independently halo or (C₁ -C₄)alkyl,

R² is (C₁ -C₄)alkyl, (C₂ -C₄)alkenyl, (C₂ -C₆)alkynyl, (C₁ -C₄)alkoxy or cyano,

R⁴ and R⁵ are each independently a hydrogen atom or (C₁ -C₄)alkyl, provided that at least one of R⁴ and R⁵ is (C₂ -C₄)alkyl and

X is halo, thiocyano or isothiocyano;

(b) a fungicidally effective amount of a second fungicidally active compound selected from the group consisting of

(i) an inhibitor of respiration at cytochrome complex III, such as a methoxyacrylate type fungicide, for example, azoxystrobin and kresoxim-methyl,

(ii) ziram

(iii) fluazinam

(iv) zarilamide

(v) chlorothalonil

(vi) propamocarb

(vii) folpet

(viii) fosetyl-aluminum or a fungitoxic metabolite thereof such as phosphorus acid,

(ix) a triphenyltin type fungicide such as fentin hydroxide and fentin acetate and

(x) a copper containing fungicide such as copper(I) sulfate, copper(II) sulfate, copper(II) sulfate pentahydrate, copper(I) oxide and Bordeaux mixture; and

(c) an agronomically acceptable carrier to the plant seed, to the plant foliage or to the growth medium for the plant.

When R⁴ and R⁵ are different, optical enantiomers of the compounds of the present invention are possible due to the presence of an asymmetric carbon atom linking R⁴ and R⁵. It is known that many biologically active compounds have optical enantiomers, one of which is more active than the other. Similarly, for compounds used in the method of the present invention, the biological activity of one enantiomer may exceed that of the other enantiomer, as described in EP 0 816 330 A1, Jan. 7, 1998.

"(C₁ -C₄)alkyl" means a straight or branched alkyl group having one to four carbon atoms per group and includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

"(C₂ -C₄)alkenyl" means a straight or branched alkenyl group having two to four carbon atoms per group and includes, for example, ethenyl, 2-propenyl, 2-butenyl, 1-methylethenyl, 2-methyl-2-propenyl and the like.

"(C₂ -C₆)alkynyl" means a straight or branched alkynyl group having from two to six carbons per group and includes, for example, ethynyl, 2-propynyl, 2-butynyl and the like.

"Halo" means chloro, fluoro, bromo and iodo.

"(C₁ -C₄)alkoxy" means a straight or branched alkoxy group having one to four carbon atoms per group and includes, for example, ethoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy and tert-butoxy.

"Cyano" means a group having the structural formula -CN.

"Thiocyano" means a group having the structural formula -SCN.

"Isothiocyano" means a group having the structural formula -NCS.

Agronomically acceptable salts include, for example, metal salts such as sodium, potassium, calcium and magnesium salts, ammonium salts such as isopropyl ammonium salts and trialkylsulfonium salts such as triethylsulfonium salts.

The first fungicidally active compound may be a single compound of formula (I) or, alternatively, may be a mixture of compounds of formula (I). Suitable compounds of formula (I) include, but are not limited to,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-ethylbenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-ethoxybenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methoxybenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-cyanobenzamide, and

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dibromo-4-methylbenzamide.

In a preferred embodiment, the first fungicidally active compound is

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dibromo-4-cyanobenzamide or a mixture thereof.

More preferably, the first fungicidally active compound is

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide.

Suitable compounds which function as the second fungicidally active compound include, but are not limited to, azoxystrobin, kresoxim-methyl, ziram, fluazinam, zarilamide, chlorothalonil, propamocarb, folpet, fosetyl-aluminum, phosphorus acid, fentin hydroxide, fentin acetate, copper(I) sulfate, copper(II) sulfate, copper(II) sulfate pentahydrate, copper(I) oxide and Bordeaux mixture.

In a preferred embodiment, the second fungicidally active compound is selected from the group consisting of fluazinam, propamocarb, folpet, fosetyl-aluminum, phosphorus acid and copper(II) sulfate pentahydrate.

The method of the present invention may optionally further comprise application of other compounds having biological activity, for example, additional fungicidally active compounds or compounds having herbicidal activity or insecticidal activity, to the plant seed, to the plant foliage or to the growth medium for the plant.

The method of the present invention is useful for the control of phytopathogenic fungi on crops and the first and second fungicidally active compounds may be applied as a soil fungicide, as a seed protectant, as a foliar fungicide or as a combination thereof. In a preferred embodiment, the first and second fungicidally active compounds are applied to a plant growth medium, to the plant seed or to plant foliage at dosage rates of from 2 parts by weight (pbw) to 90 pbw, more preferably from 5 pbw to 75 pbw, of the first fungicidally active compound per 100 pbw of the combined amount of first and second fungicidally active compounds and from 10 pbw to 98 pbw, more preferably from 25 pbw to 95 pbw, of the second fungicidally active compound per 100 pbw of the combined amount of first and second fungicidally active compounds.

As a soil fungicide, the first and second fungicidally active compositions can be incorporated in the soil or applied to the surface of the soil at a dosage rate of about 0.25 kg to 5 kg of the first fungicidally active compound and from 0.25 kg to 5 kg of the second fungicidally active compound per hectare.

As a seed protectant, the first and second fungicidally active compounds are coated on seed at a dosage rate of about 0.5 kilograms (kg) to 5 kg of the first fungicidally active compound and from 0.5 kg to 5 kg of the second fungicidally active compound per 100 kg seed.

As a foliar fungicide, the first and second fungicidally active compounds are applied to plant foliage at a dosage rate of from 0.01 kg per hectare to 5 kg per hectare of the first fungicidally active compound, and a dosage rate of from 0.01 kg per hectare to about 5 kg per hectare of the second fungicidally active compound. In a preferred embodiment, the first fungicidally active compound is applied to plant foliage at a dosage rate of from 0.05 kg per hectare to about 0.5 kg per hectare. In a preferred embodiment, the second fungicidally active compound is applied to plant foliage at a dosage rate of 0.05 kg per hectare to 5.0 kg per hectare. The first and second fungicidally active compounds can be applied to plant foliage as fungicidal sprays by methods commonly employed, such as conventional high-gallonage hydraulic sprays, low-gallonage sprays, air-blast, aerial sprays and dusts. While the dilution and rate of application will depend upon the type of equipment employed, the method and frequency of application desired and diseases to be controlled, the effective amount is typically from about 0.1 kg to about 5.0 kg, preferably 0.2 kg to 5.0 kg, of both the first and second active compounds per hectare.

The first and second fungicidally active compounds may be applied simultaneously or sequentially.

In a preferred embodiment, the first and second fungicidally active compounds are simultaneously applied to plant growth medium, the plant seed, plant foliage or a combination thereof as a composition comprising a mixture of the first fungicidally active compound and second fungicidally active compound. In the preferred embodiments, the mixture includes from 2 pbw to 90 pbw of a first fungicidally active compound and from 10 pbw to 98 pbw of a second fungicidally active compound per 100 pbw of the mixture.

In an alternative embodiment, the first and second fungicidally active compounds are applied sequentially to the plant seed, plant foliage or plant growth medium, with application of the second-applied compound following application of the first-applied compound by up to 72 hours. The compounds may be applied in either order: either the first fungicidally active compound followed by the second fungicidally active compound or, alternatively, as application of the second fungicidally active compound followed by the first fungicidally active compound.

The method of the present invention is useful in controlling certain phytopathogenic fungi, particularly fungi of the class Oomycetes, and provides high fungicidal activity and relatively low phytotoxicity. The method of the present invention is particularly effective in controlling Oomycete fungi of the genera Phytophthora, Plasmopara, Peronospora, Albungo and Pseudoperonospora, and even more particularly against the organisms of those genera that cause diseases such as late blight in tomatoes and potatoes and downy mildew in grapes and other crops, including for example, Phytophthora infestans, Plasmopara viticola and Pseudoperonospora cubensis.

For each of the above disclosed purposes, the first and second fungicidally active compounds can be used in the technical or pure form as prepared, as solutions or as formulations. The compounds are usually taken up in a carrier or are formulated so as to render them suitable for subsequent use as fungicides. For example, the compounds can be formulated as wettable powders, dry powders, emulsifiable concentrates, dusts, granular formulations, aerosols, or flowable emulsion concentrates. In such formulations, the compounds are extended with a liquid or solid carrier and, when dried, suitable surfactants are incorporated. It is usually desirable, particularly in the case of foliar spray formulations, to include adjuvants, such as wetting agents, spreading agents, dispersing agents, stickers, adhesives and the like in accordance with agricultural practices. Such adjuvants commonly used in the art can be found in McCutcheon's "Emulsifiers and Detergents", McCutcheon's "Emulsifiers and Detergents/Functional Materials" and McCutcheon's "Functional Materials" all published annually by McCutcheon Division of MC Publishing Company (New Jersey).

In general, the compositions utilized in this invention can be dissolved in appropriate solvents such as acetone, methanol, ethanol, dimethylformamide or dimethyl sulfoxide and such solutions extended with water. The concentrations of the combined first and second active compounds in the solution can vary from 1% to 90% with a preferred range being 5% to 50%.

For the preparation of emulsifiable concentrates, the compositions used in the invention can be dissolved in suitable organic solvents or a mixture of solvents, together with an emulsifying agent which permits dispersion of the first and second active compounds in water. The concentration of the combined first and second active compounds in emulsifiable concentrates is usually 10% to 90% and in flowable emulsion concentrate, this can be as high as 75%. Wettable powders suitable for spraying, can be prepared by admixing the composition with a finely divided solid, such as clays, inorganic silicates and carbonates, and silicas and incorporating wetting agents, sticking agents, and/or dispersing agents in such mixtures. The concentration of the combined first and second active compounds in such formulations is usually in the range of 20% to 98%, preferably 40% to 75%.

Dusts are prepared by mixing the composition of the present invention, or salts and complexes thereof, with finely divided inert solids which can be organic or inorganic in nature. Inert materials useful for this purpose include botanical flours, silicas, silicates, carbonates and clays. One convenient method of preparing a dust is to dilute a wettable powder with a finely divided carrier. Dust concentrations containing 20% to 80% of the combined first and second active compounds are commonly made and are subsequently diluted to 1% to 10% use concentration.

The method of the present invention, wherein an N-acetonylbenzamide and a selected second fungicidally active compound are applied to plant seed, plant foliage or to a plant growth medium, unexpectedly provides higher fungicidal activity than the same compounds used separately.

The results provided by the mixtures were compared with the predicted results that were calculated using the formula set forth by S. R. Colby in Weeds 1967, 15, 20-22 ("Colby's Formula") from the results obtained using each of the compounds individually. The predicted results are also provided in the following Examples. These examples, tables and experimental procedures are provided for guidance to the practitioner and are not meant to limit the scope of the invention which is defined by the claims.

EXAMPLE 1 Test to Control Phytophthora capsici Using N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A) and Phosphorus Acid (Compound C)

A dilution series of Compound A was prepared in dimethylsulfoxide (DMSO) and a dilution series of Compound C was prepared in sterile water. Aliquots of each were added to 25 ml of molten potato dextrose agar at 50° C. to give the appropriate concentrations shown in the table below. Immediately after adding the compound(s), the molten agar was poured into 9-cm diameter petri plates and allowed to harden. The final concentration of DMSO in all plates was 0.25%. Control plates contained DMSO but neither compound. Plates were inoculated in the center with 1 μl of a suspension of Phytophthora capsici (ATCC 15399, obtainable from the American Type Culture Collection, Rockville, Md., U.S.A.) zoospores containing 5×10⁵ zoospores per milliliter. Three replicate plates were used for each treatment. Fungal colony diameters were measured after growth for 7 days at 25° C., and two measurements were taken from each plate. Inhibition of growth was calculated by comparing growth in the treatments with compound A and/or C with growth in the controls. Degree of inhibition (Observed) is expressed as a percentage in Table 1 below. The predicted % inhibition in treatments containing both A and C was calculated using the Colby Formula.

                  TABLE 1                                                          ______________________________________                                         Control of Phytophthora capsici                                                  Compound A  Compound C                                                         Concentration Concentration % Inbibition % Inhibition                          ppm ppm (Observed) (Predicted)                                               ______________________________________                                         0         70           48.3                                                      0 100 72.1                                                                     0.2 0 34.1                                                                     0.3 0 52.8                                                                     0.2 70 75.4 65.9                                                               0.3 70 77.3 75.6                                                               0.2 100 88.1 81.6                                                              0.3 100 91.1 86.8                                                            ______________________________________                                    

EXAMPLE 2 Test to Control Phytophthora capsici Using N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A) and CuSO₄.5H₂ O (Compound D)

The test protocol followed was the same as described in Example 1 and the results reported in Table 2.

                  TABLE 2                                                          ______________________________________                                         Control of Phytophthora capsici                                                  Compound A  Compound D                                                         Concentration Concentration % Inbibition % Inhibition                          ppm ppm (Observed) (Predicted)                                               ______________________________________                                         0         100          15.3                                                      0 200 47.0                                                                     0 300 59.2                                                                     0.1 0 21.6                                                                     0.2 0 31.0                                                                     0.3 0 44.0                                                                     0.1 100 49.4 33.8                                                              0.2 100 60.9 41.8                                                              0.3 100 68.3 52.7                                                              0.1 200 84.7 58.4                                                              0.2 200 98.6 63.4                                                              0.3 200 100 70.3                                                               0.1 300 100 68.0                                                               0.2 300 100 71.8                                                               0.3 300 100 77.2                                                             ______________________________________                                    

EXAMPLE 3 N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A)+Fosetyl-aluminum (Compound E) Combination Study

Two trials were conducted with the combination of fosetyl-aluminum and N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide to evaluate the potential benefits of combinations of the two products.

The first trial was conducted to determine the appropriate rates for use in a combination of the two products.

Ratios where synergism was observed are 1:2.25, 1:4.5, 1:9, 1:18 and 1:36.

EXAMPLE 3a N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide+Fosetyl-aluminum Combination Study--Preliminary Application Rate Study

Two to three week old Bush Champion cucumbers and 2 week old Patio tomatoes were sprayed with the fungicidal compounds as protectant sprays. The plants were inoculated with cucumber downy mildew (CDM), Pseudoperonospora cubensis, and tomato late blight (TLB), Phytophthora infestans, one day after spraying.

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide was extremely effective against the tomato late blight fungus in this test. N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide alone at all rates tested gave 95% control or better. Since excellent results were observed with N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide at the rates tested, no synergism could be detected.

Cucumber downy mildew control with N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide ranged from 63 to 82%. There was a suggestion of synergism at some rates. The data suggested that the N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide rates should be lowered and the trial repeated.

Using the Colby equation, E=X+Y-XY/100, results suggest that ratios or 1:2.25 to 1:4.5 were potentially synergistic. The results of the calculations are recorded in CDM calc. column as shown in Table 3a.

                  TABLE 3a                                                         ______________________________________                                         Control of CDM and TLB                                                                                     CDM   CDM    TBL                                       obs. % calc. % obs. %                                                        Treatment kg ai/ha Control Control Control                                   ______________________________________                                         None                    0              0                                         Cmpd. E 0.112 28  30.9                                                         Cmpd. E 0.225 35  14.3                                                         Cmpd. E 0.45   54  57.1                                                        Cmpd. E 0.9  77  54.8                                                          Cmpd. A  0.0125 63  97.1                                                       Cmpd. A + Cmpd. E 0.0125 + 0.112 55 73.4 94.8                                  Cmpd. A + Cmpd. E 0.0125 + 0.225 70 75.9 90                                    Cmpd. A + Cmpd. E 0.0125 + 0.45  69 83 93.8                                    Cmpd. A + Cmpd. E 0.0125 + 0.9  81 81 92.3                                     Cmpd. A 0.025 70  96.7                                                         Cmpd. A + Cmpd. E  0.025 + 0.112 60 78.4 97.6                                  Cmpd. A + Cmpd. E  0.025 + 0.225 71 80.5 97.1                                  Cmpd. A + Cmpd. E 0.025 + 0.45 81 86.2 92.9                                    Cmpd. A + Cmpd. E 0.025 + 0.9  85.8 93.1 95.2                                  Cmpd. A 0.05  82  96.7                                                         Cmpd. A + Cmpd. E  0.05 + 0.112 61 87 95.7                                     Cmpd. A + Cmpd. E  0.05 + 0.225 76 88.6 96.7                                   Cmpd. A + Cmpd. E  0.05 + 0.45 89 91.7 96.1                                    Cmpd. A + Cmpd. E 0.05 + 0.9 87.8 95.9 96.7                                    Cmpd. A 0.1  72  97.1                                                          Cmpd. A + Cmpd. E   0.1 + 0.112 71 79.8 98.6                                   Cmpd. A + Cmpd. E   0.1 + 0.225 87 81.8 97.6                                   Cmpd. A + Cmpd. E  0.1 + 0.45 89.6 87.1 99                                     Cmpd. A + Cmpd. E  0.1 + 0.9 93.6 93.6 96.7                                  ______________________________________                                    

EXAMPLE 3b N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide+Fosetyl-aluminum Combination Study--Second Application Rate Study

As a result of the initial test, a second test was conducted against CDM with lower rates of N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide. Results with the adjusted rates confirmed the previous test with the higher doses and indicated synergism at additional rates. There was very strong synergism with some rates. Ratios were from 1:2.25 to 1:36. The results are reported in Table 3b. Specific ratios where synergism was observed were 1:2.25, 1:4.5, 1:9, 1:18 and 1:36.

                  TABLE 3b                                                         ______________________________________                                         Control of CDM                                                                                             CDM obs.                                                                               CDM .calc.                                   Treatment kg ai/ha % Control % Control                                       ______________________________________                                         None                    0                                                        Cmpd. E 0.225 14                                                               Cmpd. E 0.45   33                                                              Cmpd. E 0.9  41                                                                Cmpd. A 0.006 22                                                               Cmpd. A + Cmpd. E 0.006 + 0.225 26 32.9                                        Cmpd. A + Cmpd. E 0.006 + 0.45  49 47.7                                        Cmpd. A + Cmpd. E 0.006 + 0.9  54 54                                           Cmpd. A 0.025 14                                                               Cmpd. A + Cmpd. E 0.025 + 0.225 45 26                                          Cmpd. A + Cmpd. E 0.025 + 0.45  51 42.4                                        Cmpd. A + Cmpd. E 0.025 + 0.9  57 49.3                                         Cmpd. A 0.1  22                                                                Cmpd. A + Cmpd. E  0.1 + 0.225 47 32.9                                         Cmpd. A + Cmpd. E  0.1 + 0.45 48 47.7                                          Cmpd. A + Cmpd. E 0.1 + 0.9 60 54                                            ______________________________________                                    

EXAMPLE 4 N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A)+Propamocarb (Compound F) Tests Against TLB and CDM

Cucumber downy mildew and tomato late blight were effectively controlled with different combinations of N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide and propamocarb.

Three week old Patio variety tomato and Busch Champion cucumber plants were sprayed with the fungicide rates listed in Tables 4a and 4b. One day following application, the plants were inoculated with spore 30-40×10⁴ spores/ml suspensions of the respective diseases. The plants were incubated in mist cabinets for twenty-four hours and then placed in control temperature chambers for the duration of the experiment.

Visual assessments of disease infection was conducted and the transformed to percent control values. The data in Tables 4a and 4b suggest strong levels of synergism with the combinations. Ratios of N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide to propamocarb ranged from 1:1 to 1:42. Synergism was seen at the ratios: 1:42, 1:21, 1:10.5, 1:5, 1:2.5 and 1:1.

                  TABLE 4a                                                         ______________________________________                                         Tomato Late Blight Control                                                                                  % Control                                                                              % Control                                   Treatment Kg ai/ha Observed Calculated                                       ______________________________________                                         Cmpd. F      0.063       0                                                        0.125 3                                                                        0.25   17                                                                     Cmpd. A 0.006 23                                                                0.012 20                                                                       0.025 36                                                                      Cmpd. A + Cmpd. F 0.006 + 0.063 31 23                                           0.006 + 0.125 37 27                                                            0.006 + 0.25  60 36                                                           Cmpd. A + Cmpd. F 0.012 + 0.063 42 20                                           0.012 + 0.125 34 22                                                            0.012 + 0.25  47 34                                                           Cmpd. A + Cmpd. F 0.025 + 0.063 37 36                                           0.025 + 0.125 50 38                                                            0.025 + 0.125 54 47                                                         ______________________________________                                    

                  TABLE 4b                                                         ______________________________________                                         Cucumber Downy Mildew Control                                                                               % Control                                                                              % Control                                   Treatment Kg ai/ha Observed Calculated                                       ______________________________________                                         Cmpd. F      0.063       9                                                        0.125 0                                                                        0.25   27                                                                     Cmpd. A 0.006 56                                                                0.012 33                                                                       0.025 45                                                                      Cmpd. A + Cmpd. F 0.006 + 0.063 66 60                                           0.006 + 0.125 67 56                                                            0.006 + 0.25  67 55                                                           Cmpd. A + Cmpd. F 0.012 + 0.063 57 39                                           0.012 + 0.125 47 33                                                            0.012 + 0.25  42 51                                                           Cmpd. A + Cmpd. F 0.025 + 0.063 77 50                                           0.025 + 0.125 82 45                                                            0.025 + 0.25  86 60                                                         ______________________________________                                    

EXAMPLE 5a N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A)+Folpet (Compound G) Tests Against CDM

The results in the accompanying Table 5a are for N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide and folpet. The test was conducted as using the standard protocol (Example 3a) for cucumber downy mildew. Treatments were evaluated as a 3-day residual application.

Synergism was observed at the following ratios of N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide to folpet for CDM disease: 1:4.5, 1:9 and 1:18. The results are reported in Table 5a.

                  TABLE 5a                                                         ______________________________________                                         Cucumber Downy Mildew Control                                                                          Number of                                                                               % Control                                                                             % Control                                Treatment Kg ai/ha Infection Sites Observed Calculated                       ______________________________________                                         Cmpd. G  0.113      16         28.8                                               0.225 22.2 0                                                                   0.45   19.2 8.5                                                               Cmpd. A 0.025 5.4 74.3                                                          0.05  3.2 84.8                                                                 0.1  0.4 98.1                                                                 Cmpd. A + 0.025 + 0.225 3.6 82.9 74.3                                          Cmpd. G 0.025 + 0.45  2.2 89.5 76.5                                            Cmpd. A +  0.05 + 0.225 2.2 89.5 84.8                                          Cmpd. G 0.05 + 0.45 2.2 89.5 84.8                                            ______________________________________                                    

EXAMPLE 5b N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A)+Folpet (Compound G) Tests Against PLB

Three to four week old potato seedlings were sprayed with a series of doses of folpet and N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide. Individual treatments and combination treatments were compared for biological efficacy against Phytophthora infestans on potatoes (PLB). Fungicide solutions were sprayed and inoculated one day after the application. Inoculation was completed with a spore suspension of 30-40×10⁴ spores/ml. The plants were placed in a misting cabinet for 24 hours. Following the infection period, plants were placed in a constant temperature chamber for the duration.

One day following application, the plants were inoculated with spore suspensions of the respective diseases. The plants were inoculated in mist cabinets for twenty-four hours and then placed in control temperature chambers for the duration of the experiment.

Disease pressure was very high in this test as is evidenced by the exceptionally low level of control expressed by the individual treatment. However, the combinations were more active than either of the fungicides used alone.

N-[3-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide and folpet at ratios of 1:2.25, 1:4.5 and 1:9 exhibited synergism in this test. The results are reported in Table 5b.

                  TABLE 5b                                                         ______________________________________                                         Potato Late Blight Control                                                                                  % Control                                                                              % Control                                   Treatment Kg ai/ha Observed Calculated                                       ______________________________________                                         Cmpd. G       0.225      0                                                        0.45 3.5                                                                      Cmpd. A 0.05 12                                                                 0.10 16                                                                       Cmpd. A + Cmpd. G 0.05 + 0.225 32 12                                            0.05 + 0.45  20 15                                                            Cmpd. A + Cmpd. G 0.10 + 0.225 21 16                                            0.10 + 0.45  39 19                                                          ______________________________________                                    

EXAMPLE 6a N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A)+Fluazinam (Compound H) Test Against TLB

The results in the accompanying Table 6a are for N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide and fluazinam against TLB. The test was conducted as using the standard protocol (Example 3a) for tomato late blight. Treatments were applied as one day protectant applications.

Synergism was observed at the 1:5 ratio of N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide to fluazinam. The results are reported in Table 6a.

                  TABLE 6a                                                         ______________________________________                                         Tomato Late Blight Control                                                                                % In- % Control                                                                             % Control                                Treatment Kg ai/ha fection Observed Calculated                               ______________________________________                                         Cmpd. H     0.125      64      20                                                Cmpd. A 0.025 13.2 84                                                          Cmpd. A + Cmpd. H 0.025 + 0.125 6.2 92 87.6                                  ______________________________________                                    

EXAMPLE 6b N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A)+Fluazinam (Compound H) Test Against GDM

An example of synergism was observed with fluazinam in a test against grape downy mildew, Plasmopara viticola.

Tissue culture produced from Delaware grapes were sprayed with the fungicides. Inoculation with grape downy mildew (GDM) spores having a concentration of 40,000 spores ml was conducted 1 day after the application. Plants were placed in a mist chamber for 24 hrs and then moved to a control temperature chamber for the remainder of the test period. The results are reported in Table 6b.

                  TABLE 6b                                                         ______________________________________                                         Grape Downy Mildew Control                                                                                  % Control                                                                              % Control                                   Treatment Kg ai/ha Observed Calculated                                       ______________________________________                                         Cmpd. H      0.006       52                                                      Cmpd. A 0.006 22                                                               Cmpd. A + Cmpd. H 0.006 + 0.006 76 63                                        ______________________________________                                    

It is to be understood that changes and variations in this invention may be made without departing from the spirit and scope of this invention as defined by the appended claims. 

What is claimed is:
 1. A fungicidal composition comprising synergistic fungicidally effective amounts of(a) a first fungicidally active compound having the formula ##STR3## or an agronomically acceptable salt thereof whereinR¹ and R³ are each chloro, R² is methyl, R⁴ is methyl, R⁵ is ethyl, and X is chloro; (b) the second fungicidally active compound; and (c) an agronomically acceptable carrier.
 2. A method for controlling phytopathogenic fungi on a plant comprising the application of a synergistic fungicidally effective amount of the composition of claim 1 to the plant seed, to the plant foliage or to the growth medium for the plant.
 3. The method of claim 2 wherein the phytopathogenic fungi belong to the class Oomycetes and are of the genera Phytophthora, Plasmopara, Peronospora, Albugo or Pseudoperonospora.
 4. The method of claim 2 wherein the plant is a potato plant, a tomato plant, a grape plant or a cucumber plant.
 5. The method of claim 2 wherein the amounts of the first and second fungicidally active compounds applied comprise from 2 parts by weight to 90 parts by weight of the first fungicidally active compound and from 10 parts by weight to 98 parts by weight of the second fungicidally active compound per 100 parts by weight of the combined amount of the first and second fungicidally active compounds. 